Sheet-metal-cuttingr tool



March 22, 1927.

F. J. MCFARLAND SHEET METAL CUTTING TOOL Filed Jan. 9 1926 am nu l/z l f Patented Mar. 22, 1927.

PATENT OFFICE.

FRDRIGK J. MCFARLAND, OF BREMERTON, UTASHINGTON.

SHEET-METAL-CUTTING TOOL.

Application filed January This invention relates to tools for cutting sheet metal and one of the objects pf this invention is to provide a tool for this purpose which may be driven through the sheet metal either by hand or by a steam, pneu.- matic or electric hammer.

A further object of the invention is to provide a tool of this character which will make perfect `cuts of all kinds either straight or curved, right or left, inside or outside, circles of any size larger than one inch in diameter, and will eut right angles or any other cut desired by the operator and which will leave the edges of the metal free from r burr, the tool being further capable of cutting an extremely small shaving from the edge of the sheet just as well as it will split` the largest sheet.

Still another object is attained by this tool is that the sheets do not have to be turned or handled while being cutand the tool will eut sheet metal in places inaccessible to other tools without removing the metal from its permanent location.

Myv invention is illustrated in the accompanying drawings wherein Figure 1 is a top plan view of a tool constructed in accordance with my invention;

Figure 2 is a section on the line 2-2 of Figure 1;

Figure 3 is a section on the line 3--3` of Figure l;

Figure 4 is a section on the line 4 4 of Figure 1;

Figure 5 is a side elevation of the tool constructed in-accordance with my invention;

Figure 6 is a section on the line G-6 of Figure 5;

Figure 7 is a section on the line Tw-7 of Figure 5; i

Figure 8 is a section on the line 8--8 of Figure 5; f

Figure 9 is a front elevation of the cutting tool.

Referring to these drawings it will be seen that the tool comprises a shank 10, which shank is preferably hexagonal in cross section. The cross sectional area of they shank 10 and the length of the shank will depend, of course, u on the work to be accomplished. The shank 1s formed at one end with a cuttiner headformed te provide two wings 11 mi in?, which @a ai@ am. eef-s er siga-e .t

9, 1.926. Serial No. 80,289.

are laterally offset with regard to each other so that the inner fiat face 13 of the upper wing coincides with the inner flat face 14 of the lower wing. rlhe lower wing 12 is eX- tended in advance of the upper wing 11 and is somewhat pointed at its extremity while the upper wing 11 is rounded at its ext-rem- It will be seen from Figure 5 that the inner edge faces 15 and 16 of the head constitute two sides of a reentrant angle, the apenof this angle being disposed approximately on the line 7 7 of Figure 5. One side face. of each blade or wing 11 and 12 is flat, as before remarked, and the top and bottom faces are deformations or modifications of the faces of the hexagonal shank 10.

.lhis tool is to be formed of steel and the point of the wing 12 is to be driven into the metal so that the sheet of metal will be disposed at right angles to the faces 13 and 14 and against the apex of the reentrant angle formed by the faces 15 and 16, this angle being (for a tool capable of use for sheet metal having a thickness of .0625 mill. or less) approximately 22.

For making cuts that have their beginning at the edge or margin of the sheet the reentrant angle or cutting edge of the tool is disposed against the edge of the sheet at the desired point, keeping the shank of the tool almost parallel with the surface of the sheet. The tool is then driven through the sheet by means of a hammer following the desired line. This will force the sheet on one side, under one blade or wing of the tool and on the. other side above the other blade or wing. If the shank is held exactly parallel to the surface of thesheet being eut, both cutting edges of the sheet will be slightly curved but if the shank of the tool is held at an angle equal to the angle of one side of the V--shaped notch 1G, `the lower sheet will he left perfectly smooth and straight while the other side of the cut will be curved thus giving clearance for the `operators hammer and hand.

For cuts that are wholly wit-hin the sheet and do not reach the margin or edge of the sheet the longer and pointed end 15 of the blade 12 is placed against the sheet near the starting point of the cut desired and the shank of the tool is kept at about 90 from the ef sheet. The tool is then driven inward until the point of the blade punctures the sheet and then continue driving and bring the shank of the tool down until it is almost parallel with the surface of the sheet, following the `line of desired cut. Y

vIn making short curves the tool will ad-` just itself to the proper lateral angle to make the desired curve, requiring only guiding and driving by the operator to make the cut desired.V

As above stated, the long pointed blade or Wing 12`as shown in Figure 5 is used for puncturing the sheet Where thecut is Wholly Within the sheet. This requires the upper blade 13 to be yrounded on its edgein order to slide lon top of the sheet and not dig in thus letting the sheet reach the apex of the V`shaped notch or cutting edge of the tool freely. -Both.bladesrecede from the center line of the shank from the apex of the. V-

shaped notch to the point Wherer the blades merge intothc shank, thus giving the clearance required in cutting small circles and sharp curves.- Y v This device Willmalre smooth cuts ot' all kinds-either inra curvedfror straight line atv the option ofi the Workman, and can be ldriven forward With a commen hammer or by a pneumatic or electric'hammerand will make right angulary cuts with the same facility that it does curved orstraight cuts. actua-l practice it has been fou-nd that this tool will do the Work of expensive power machines in less than `one half' the time and accomplish much better results. The-edges of the metal will bevfree from anyI burr and even small shavings may. be cu-t from the edgeof the sheet with case. The sheets do n-otlhave to 'be turned or handled While being cutbutvmay be simply laid on a bench or door and cut by a'single operator without help or assistance. The teol does not re-V quire sharpening, at least for a very long time. Y Y

In actual practice it has been found? that Y fused with a small' sized pneumatic hannner theAV tool Wil-lf cut 17 cf Q2 gauge galvanized iron per minute, lill/ of 20 gauge galvanized iron per minute', 97' of' 18 gauge,y G" o-f 16 gauge and 21/2. of ll gauge ln'aminute, While With lthe larger size pneumatic vhammer it will cut e36!" Vthick plate easily. This tool has been used tocutal hole having a eir-V cumference of 100 Vin the center-cf avsheet 1 of 18 gaugegalvanized' steel and has cut this hole in one and one half minutes with only f one person employed-While Witli-ahammer and coldichisel and file to `smooth thecut the besty time made. Was thirty minutesl by one 'mechanic and one helper. Furthermore, this toolA Will cut sheet'y metal in places inaeces siblel to other tools Without any necessity of removing thel sheetbeing cut. Thus, it may vbe used fori cutting holes in pipes, boiler# cases, etc., Withoutl removing them from their permanent locations. Obviously the tool will be made in larger or smaller sizes and the blades or Wings Will also vary in their dimensions and Lin the angle which the tWo faces V15 and 16 bear to each other.

I do not Wish to be limited to the exactY Y formation of the tool as illustrated, as this 'may be varied in many Ways without departother, the inner face of each blade `beingffat andY disposed in approximatelythe same plane. Y

2. A sheet metal cutting tool-having a shank and a cutting head, the cutting head beingformed with upper and lower wings-er blades, the wings being" laterally lofs'et with relation to each other, andthe inner edges of the Wings being extended convergently inwardinto intersecting relation. f Y i 3. A sheet metal cuttingfteol rhavinga shank and a-cutt-ing head formedl thereon,

the `cutting head being formed te 'provide upper and lovverv laterally .opposed` blades, the inner faeesof each blade being flatand 'the innerfaces of both blades being 'disposed in the same plane, the bladesat their for- Y Ward ends beinglseparated bya-reentrantly angled opening, andi the liofvveibladeor Wing cxtendingbeyond the upperblade orwing.

4. A- sheet metal cutting' tool having a shank and cutting head, the cutting 'head being` widened and flattened and twistedy with relation -tolthefshank to provide two Wings or blades disposed in ofset relation to each other and formed to lprovide flat inner faces disposed in the same plane, the

integral andA laterally offset with relation to each other.

6'. A sheet meta-l 4cuttingf tnol having a shank and a cutting l'ieachthe cutting headV beingl flattened `.to provide two Wings or blades disposed in laterally offset` 'relationito each Vother and formedto provide fiatinner faces disposed in the-same plane, the upperV Wingat its forward` end being pointed and upper Wing'at-its forwardend bci-111g rounded said? up per Y extended beyond the upper Wing, said upperv and lower Wings or blades having their inner edge laces reentrantly angled and transversely inclined, the transversely inclined faces of shank from the apex of the V-shaped notch to the point Where the blades merge into the shank.

signature.

FREDRICK J. MGFARLAND.

In testimony whereof I hereunto alix my 

